docs: clarify cancel and pause capabilities for scheduled sends

docs/use-cases/README.md

@@ -15,7 +15,7 @@ This documentation provides examples for specific Twilio SendGrid v3 API use cas
   * [Attachments](attachments.md)
   * [Customization Per Recipient](customization.md)
   * [Manually Providing Content](manual-content.md)
-  * [Specifying Time to Send At](time-to-send.md)
+  * [Scheduled Send](scheduled-send.md)
   * [Specifying Custom Headers](custom-headers.md)
   * [Specifying Categories](categories.md)
   * [Timeout](timeout.md)

docs/use-cases/scheduled-send.md

@@ -0,0 +1,38 @@
+# Creating a Scheduled Send
+
+Use the `sendAt` property to specify when to send the emails (in [UNIX timestamp](https://en.wikipedia.org/wiki/Unix_time) seconds, not milliseconds):
+
+```js
+const msg = {
+  to: '[email protected]',
+  from: '[email protected]',
+  subject: 'Hello delayed email',
+  html: '<p>Some email content</p>',
+  sendAt: 1500077141,
+};
+
+await sgMail.send(msg);
+```
+
+## Limitations
+
+1. Emails can only be scheduled, at most, 72 hours in advance.
+2. If successful, without a `batchId` set, the call to `sgMail.send()` returns a 202 status code with an empty response body. Currently, cancelling a scheduled email without a `batchId` set [requires a change of password or contacting our support team](https://sendgrid.com/docs/for-developers/sending-email/stopping-an-in-progress-send/#stopping-transactional-email).
+
+## [To Cancel or Pause Your Scheduled Send](https://sendgrid.com/docs/for-developers/sending-email/stopping-a-scheduled-send/#canceling-transactional-email):
+
+1. Create a [Batch ID](https://github.com/sendgrid/sendgrid-nodejs/blob/master/packages/client/USAGE.md#create-a-batch-id).
+2. Assign Batch ID to a `msg` object:
+```js
+const msg = {
+  to: '[email protected]',
+  from: '[email protected]',
+  subject: 'Hello delayed email',
+  html: '<p>Some email content</p>',
+  sendAt: 1500077141,
+  batchId: 'YOUR_BATCH_ID'
+};
+
+await sgMail.send(msg);
+```
+3. [Update your Batch ID](https://github.com/sendgrid/sendgrid-nodejs/blob/master/packages/client/USAGE.md#post-userscheduled_sends) with a `cancel` or `pause` status.